High-dimensional non-orthogonal transmission method

ABSTRACT

A high-dimensional non-orthogonal transmission method is provided. In the method, signals of various users are mapped to form high-dimensional signals, and the high-dimensional signals are pre-coded, such that non-orthogonal transmission is realized in a higher dimension. Moreover, different users perform matched receiving on respective signals, and non-orthogonal transmission signals can be recovered merely by means of a receiver with a linear complexity. By means of the method, multi-user data non-orthogonal transmission can be realized without depending on conditions such as user pairing and collaboration, and various users do not need to perform iterative feedback, such that the detection complexity of non-orthogonal multi-user signals is significantly reduced.

CROSS REFERENCE TO THE RELATED APPLICATIONS

This application is the national phase entry of InternationalApplication No. PCT/CN2021/090967, filed on Apr. 29, 2021, which isbased upon and claims priority to Chinese Patent Application No.202011249750.4, filed on Nov. 11, 2020, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention belongs to the field of telecommunications, and inparticular, relates to a high-dimensional non-orthogonal transmissionmethod.

BACKGROUND

In the past few years, non-orthogonal multiple access (NOMA) hasattracted much attention as a candidate technology for LTE, 5G andbeyond 5G. In NOMA, multiple pieces of user equipment (UE) realizescollaboration and share time domain, frequency domain and code domainchannel resources. 3GPP considered different applications of NOMA.Academia and industry have also proposed various SCMA system, such aspower domain NOMA, sparse code multiple access (SCMA), modular divisionmultiple access (PDMA), resource extended multiple access (RSMA) and thelike. Through reasonable configuration, NOMA can obtain higher usercapacity than orthogonal multiple access (OMA). However, the corechallenges of the existing NOMA technology lie in the need for higherreceiver complexity, user pairing and user collaboration complexity, andthe detection complexity increases rapidly as the number of UEincreases.

SUMMARY

To solve the above problem, the present invention provides ahigh-dimensional non-orthogonal transmission method. Multi-user datanon-orthogonal transmission can be realized without depending onconditions of user pairing and collaboration, various users do not needto perform iterative feedback, and data can be recovered only throughcommon coherent reception, such that the signal detection complexity issignificantly reduced.

The present invention discloses a high-dimensional non-orthogonaltransmission method. In the method, a transmitter, a plurality of usersand a plurality of channel resources are provided; the transmitter isconfigured to process and transmit original signals of the plurality ofusers; the plurality of users receive and recover respective originalsignals; and the plurality of channel resources include the time-domain,the frequency-domain, and the space-domain resources, for thetransmitter and the plurality of users to use.

The high-dimensional non-orthogonal transmission method includes thefollowing steps:

step 1: mapping, by the transmitter, an original signal of a u^(th) userto a u^(th) high-dimensional original signal, where the u^(th)high-dimensional original signal is as follows:

${{s(u)} = \begin{bmatrix}{s_{1}(u)} \\{s_{2}(u)} \\ \vdots \\{s_{M}(u)}\end{bmatrix}},{{s_{1}(u)} = {{s_{2}(u)} = {\ldots = {{s_{M}(u)} = \frac{s_{0}(u)}{\sqrt{M}}}}}}$

where s₀(u) represents the original signal of the u^(th) user, s(u)represents the u^(th) high-dimensional original signal, s₁(u) representsthe i^(th) dimension of the u^(th) high-dimensional original signal,i=1, 2, . . . , M, and M represents the dimension of the u^(th)high-dimensional original signal and has a value equal to the number ofthe channel resources;

step 2: precoding, by the transmitter, the u^(th) high-dimensionaloriginal signal to generate a u^(th) high-dimensional transmissionsignal, where the precoding is as follows:

${x(u)} = {\begin{bmatrix}{x_{1}(u)} \\{x_{2}(u)} \\ \vdots \\{x_{M}(u)}\end{bmatrix} = \begin{bmatrix}{{s_{1}(u)}{\alpha_{1}(u)}} \\{s_{2}(u)\alpha_{2}(u)} \\ \vdots \\{s_{M}(u)\alpha_{M}(u)}\end{bmatrix}}$

where x(u) represents the u^(th) high-dimensional transmission signal,x_(i)(u) represents the i^(th) dimension of the u^(th) high-dimensionaltransmission signal, and α_(i)(u) represents the i^(th) dimension of au^(th) precoding signal;

step 3: summing up, by the transmitter, all u^(th) high-dimensionaltransmission signals to obtain a total high-dimensional transmissionsignal:

$\overset{\sim}{x} = {\sum\limits_{u = 1}^{U}{x(u)}}$

where U represents the number of the users, and {tilde over (x)}represents the total high-dimensional transmission signal; broadcasting,by the transmitter, the total high-dimensional transmission signal toall the users using the plurality of channel resources, where one of theplurality of channel resources is used to transmit one dimension of thetotal high-dimensional transmission signal; and

-   -   step 4: receiving, by the u^(th) user, the total        high-dimensional transmission signal to obtain a total        high-dimensional received signal, and performing matched        receiving on the total high-dimensional received signal        according to the u^(th) precoding signal to obtain an estimation        of the u^(th) original signal, where u=1, 2, . . . , U, and a        matched receiving process is as follows:

$\hat{\overset{\sim}{x}} = \begin{bmatrix}{\hat{\overset{\sim}{x}}}_{1} \\{\hat{\overset{\sim}{x}}}_{2} \\ \vdots \\{\hat{\overset{\sim}{x}}}_{M}\end{bmatrix}$${{\hat{s}}_{0}(u)} = {\sum\limits_{i = 1}^{M}{{\alpha_{i}^{*}(u)}{\hat{\overset{\sim}{x}}}_{i}}}$

where ŝ₀(u) represents an estimation of the u^(th) original signal,α_(i)*(u) represents conjugation of the i^(th) dimension of the u^(th)precoding signal, {tilde over ({circumflex over (x)})} represents thetotal high-dimensional received signal, {tilde over ({circumflex over(x)})}_(i) represents the i^(th) dimension of the total high-dimensionalreceived signal, and i=1, 2, . . . , M.

Further, the i^(th) dimension of the u^(th) precoding signal in step 2is as follows:

${\alpha_{i}(u)} = {\prod\limits_{k = 1}^{L}{\exp\left( \frac{j2\pi\left( {m_{k} - 1} \right)\Delta{f_{k}\left( {u - 1} \right)}T}{U} \right)}}$

then the u^(th) precoding signal is as follows:

${\alpha(u)} = \begin{bmatrix}{\alpha_{1}(u)} \\{\alpha_{2}(u)} \\ \vdots \\{\alpha_{M}(u)}\end{bmatrix}$

where J represents an imaginary unit, L represents the number ofprecoding layers, m_(k) represents a k^(th) layer of precoding branchindexes, and the number k of the precoding layers and the k^(th) layerof precoding branch indexes m k satisfy:

1 ≤ m_(k) ≤ M_(k)${m_{L} + {\sum\limits_{k = 1}^{L - 1}\left\lbrack {\left( {m_{k} - 1} \right){\prod}_{l = {k + 1}}^{L}M_{l}} \right\rbrack}} = i$${\prod\limits_{k = 1}^{L}M_{k}} = M$

where M_(k) represents the number of the k^(th) layer of precodingbranches, Δf_(k) represents the let layer of frequency offsets and has avalue determined in advance, k=1, 2, . . . L, T represents an offsetperiod and has a value as follows:

$T = \frac{1}{gc{d\left( {{\Delta f_{1}},{\Delta f_{2}},\ldots,{\Delta f_{L}}} \right)}}$

gcd(Δf₁, Δf₂, . . . , Δf_(L)) represents the greatest common divisor ofΔf₁, Δf₂, . . . , Δf_(L).

In the present invention, signals of a plurality of users are mapped toform high-dimensional signals, and the high-dimensional signals arepre-coded, such that non-orthogonal transmission is realized in a higherdimension. Moreover, different users perform matched receiving onrespective signals, and non-orthogonal transmission signals can berecovered with a receiver with merely a linear complexity. Furthermore,by means of the method disclosed in the present invention, multi-userdata non-orthogonal transmission can be realized without depending onmethods such as user pairing and collaboration, and the users do notneed to perform iterative feedback, such that the detection complexityof non-orthogonal multi-user signals is significantly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural block diagram of a transmitter;

FIG. 2 is a block diagram of a u^(th) user of a plurality of users; and

FIG. 3 is a multi-user communication error rate performance curve when64 channel sources are used.

DETAILED DESCRIPTION OF THE EMBODIMENTS

A specific embodiment of the present invention will be given below. Inthis embodiment, it is assumed that the number of users is: U=80 and thenumber of channel resources is 64, where the channel resources herespecifically refer to frequency-domain subcarriers. The number ofprecoding layers is: L=2, the number of the first layer of precodingbranches is: M₁=8, the number of the second layer of precoding branchesis: M₂=8, the first layer of frequency offsets is: Δf₁=100 kHz, and thesecond layer of frequency offsets is: Δf₂=200 kHz. A transmittertransmits signals according to the following steps:

The transmitter adopts a system structure shown in FIG. 1 . Firstly, anoriginal signal of a u^(th) user is mapped to form a u^(th)high-dimensional original signal, where the u^(th) high-dimensionaloriginal signal is as follows:

${{s(u)} = \begin{bmatrix}\begin{matrix}\begin{matrix}{s_{1}(u)} \\{s_{2}(u)}\end{matrix} \\ \vdots \end{matrix} \\{s_{64}(u)}\end{bmatrix}},{{s_{1}(u)} = {{s_{2}(u)} = {\ldots = {{s_{64}(u)} = \frac{s_{0}(u)}{\sqrt{64}}}}}}$

The transmitter precodes the u^(th) high-dimensional original signal togenerate a u^(th) high-dimensional transmission signal. A precodingprocess is as follows:

${x(u)} = {\begin{bmatrix}\begin{matrix}\begin{matrix}{x_{1}(u)} \\{x_{2}(u)}\end{matrix} \\ \vdots \end{matrix} \\{x_{64}(u)}\end{bmatrix} = \begin{bmatrix}\begin{matrix}\begin{matrix}{{s_{1}(u)}{\alpha_{1}(u)}} \\{s_{2}(u)\alpha_{2}(u)}\end{matrix} \\ \vdots \end{matrix} \\{{s_{64}(u)}{\alpha_{64}(u)}}\end{bmatrix}}$

where x(u) represents the u^(th) high-dimensional transmission signal,the u^(th) precoding signal is generated according to a generationstructure shown in FIG. 3 , and the i^(th) dimension of the u^(th)precoding signal is as follows:

${{\alpha_{i}(u)} = {{\exp\left( \frac{j2{\pi\left( {m_{1} - 1} \right)}\Delta{f_{1}\left( {u - 1} \right)}T}{80} \right)}{\exp\left( \frac{j2{\pi\left( {m_{2} - 1} \right)}\Delta{f_{2}\left( {u - 1} \right)}T}{80} \right)}}},$$T = {10\mu s\left\{ \begin{matrix}{{{8\left( {m_{1} - 1} \right)} + m_{2}} = i} \\{0 \leq m_{1} \leq 8} \\{0 \leq m_{2} \leq 8}\end{matrix} \right.}$

A receiver of the u^(th) user of the plurality of users adopts the blockdiagram shown in FIG. 2 . The transmitter sums up all the u^(th)high-dimensional transmission signals to obtain a total high-dimensionaltransmission signal:

$\overset{˜}{x} = {\sum\limits_{u = 1}^{U}{x(u)}}$

The u^(th) user of the plurality of users receives the totalhigh-dimensional transmission signal to obtain a total high-dimensionalreceived signal, matched receiving is performed on the totalhigh-dimensional received signal according to the u^(th) precodingsignal to obtain an estimation of the u^(th) original signal. A matchedreceiving process is as follows:

$\overset{\hat{\sim}}{x} = \begin{bmatrix}\begin{matrix}\begin{matrix}{\overset{\hat{\sim}}{x}}_{1} \\{\overset{\hat{\sim}}{x}}_{2}\end{matrix} \\ \vdots \end{matrix} \\{\overset{\hat{\sim}}{x}}_{M}\end{bmatrix}$${{\overset{\hat{}}{s}}_{0}(u)} = {\sum\limits_{i = 1}^{M}{{a_{i}^{*}(u)}{\overset{\hat{˜}}{x}}_{i}}}$

where ŝ₀(u) represents an estimation for the u^(th) original signal, andα_(i)*(u) represents conjugation of the i^(th) dimension of the u^(th)precoding signal and has a value as follows:

${{\alpha_{i}^{*}(u)} = {{\exp\left( {- \frac{j2{\pi\left( {m_{1} - 1} \right)}\Delta{f_{1}\left( {u - 1} \right)}T}{80}} \right)}{\exp\left( {- \frac{j2{\pi\left( {m_{2} - 1} \right)}\Delta{f_{2}\left( {u - 1} \right)}T}{80}} \right)}}},$$T = {10\mu s\left\{ \begin{matrix}{{{8\left( {m_{1} - 1} \right)} + m_{2}} = i} \\{0 \leq m_{1} \leq 8} \\{0 \leq m_{2} \leq 8}\end{matrix} \right.}$

FIG. 3 is a multi-user communication error rate performance curve when64 channel sources are used in this embodiment. It can be seen that byadoption of the non-orthogonal transmission method provided by thisembodiment, communication with more than 64 users can be realized;furthermore, the detection method provided by this embodiment only needsto perform correlation and addition operations. The detection methoddoes not need user pairing, collaboration and iterative feedback, andonly has a linear complexity.

1. A high-dimensional non-orthogonal transmission method, wherein in themethod, a transmitter, a plurality of users and a plurality of channelresources are provided; the transmitter is configured to process andtransmit original signals of the plurality of users; the plurality ofusers receive and recover respective original signals; the plurality ofchannel resources comprise a time-domain, a frequency-domain and aspace-domain resources, for the transmitter and the plurality of usersto use; the high-dimensional non-orthogonal transmission methodcomprises the following steps: step 1: mapping, by the transmitter, anoriginal signal of a u^(th) user to a u^(th) high-dimensional originalsignal, wherein the u^(th) high-dimensional original signal is asfollows: ${{s(u)} = \begin{bmatrix}\begin{matrix}\begin{matrix}{s_{1}(u)} \\{s_{2}(u)}\end{matrix} \\ \vdots \end{matrix} \\{s_{M}(u)}\end{bmatrix}},{{s_{1}(u)} = {{s_{2}(u)} = {\ldots = {{s_{M}(u)} = \frac{s_{0}(u)}{\sqrt{M}}}}}}$wherein s₀(u) represents the original signal of the u^(th) user, s(u)represents the u^(th) high-dimensional original signal, s₁(u) representsan i^(th) dimension of the u^(th) high-dimensional original signal, i=1,2, . . . , M, and M represents a dimension of the u^(th)high-dimensional original signal and has a value equal to a number ofthe channel resources; step 2: precoding, by the transmitter, the u^(th)high-dimensional original signal to generate a u^(th) high-dimensionaltransmission signal, wherein a precoding process is as follows:${x(u)} = {\begin{bmatrix}\begin{matrix}\begin{matrix}{x_{1}(u)} \\{x_{2}(u)}\end{matrix} \\ \vdots \end{matrix} \\{x_{M}(u)}\end{bmatrix} = \begin{bmatrix}\begin{matrix}\begin{matrix}{{s_{1}(u)}{\alpha_{1}(u)}} \\{s_{2}(u)\alpha_{2}(u)}\end{matrix} \\ \vdots \end{matrix} \\{{s_{M}(u)}{\alpha_{M}(u)}}\end{bmatrix}}$ wherein x(u) represents the u^(th) high-dimensionaltransmission signal, x_(i)(u) represents a i^(th) dimension of theu^(th) high-dimensional transmission signal, and α₁(u) represents ai^(th) dimension of a u^(th) precoding signal; step 3: summing up, bythe transmitter, all u^(th) high-dimensional transmission signals toobtain a total high-dimensional transmission signal:$\overset{˜}{x} = {\sum\limits_{u = 1}^{U}{x(u)}}$ wherein U representsa number of the users, and {tilde over (x)} represents the totalhigh-dimensional transmission signal; broadcasting, by the transmitter,the total high-dimensional transmission signal to all the users by theplurality of channel resources, wherein one of the plurality of channelresources is used to transmit one dimension of the high-dimensionaltransmission signal; and step 4: receiving, by the u^(th) user, thetotal high-dimensional transmission signal to obtain a totalhigh-dimensional received signal, and performing matched receiving onthe total high-dimensional received signal according to the u^(th)precoding signal to obtain an estimation of a u^(th) original signal,wherein u=1, 2, . . . , U, and a matched receiving process is asfollows: $\overset{\hat{\sim}}{x} = \begin{bmatrix}\begin{matrix}\begin{matrix}{\overset{\hat{\sim}}{x}}_{1} \\{\overset{\hat{\sim}}{x}}_{2}\end{matrix} \\ \vdots \end{matrix} \\{\overset{\hat{\sim}}{x}}_{M}\end{bmatrix}$${{\overset{\hat{}}{s}}_{0}(u)} = {\sum\limits_{i = 1}^{M}{{a_{i}^{*}(u)}{\overset{\hat{˜}}{x}}_{i}}}$wherein ŝ₀(u) represents the estimation of the u^(th) original signal,α_(i)*(u) represents a conjugation of the i^(th) dimension of the u^(th)precoding signal, {tilde over ({circumflex over (x)})} represents thetotal high-dimensional received signal, {tilde over ({circumflex over(x)})}_(i) represents an i^(th) dimension of the total high-dimensionalsignal, and i=1, 2, . . . , M.
 2. The high-dimensional non-orthogonaltransmission method according to claim 1, wherein in step 2, the i^(th)dimension of the u^(th) precoding signal is as follows:${\alpha_{i}(u)} = {\prod\limits_{k = 1}^{L}{\exp\left( \frac{j2{\pi\left( {m_{k} - 1} \right)}\Delta{f_{k}\left( {u - 1} \right)}T}{U} \right)}}$then a u^(th) precoded signal is as follows:${\alpha(u)} = \begin{bmatrix}\begin{matrix}\begin{matrix}{\alpha_{1}(u)} \\{\alpha_{2}(u)}\end{matrix} \\ \vdots \end{matrix} \\{\alpha_{M}(u)}\end{bmatrix}$ wherein j represents an imaginary unit, L represents anumber of precoding layers, m_(k) represents a k^(th) layer of precodingbranch indexes, and a number k of the precoding layers and the k^(th)layer of precoding branch indexes m k satisfy: 1 ≤ m_(k) ≤ M_(k)${m_{L} + {\sum\limits_{k = 1}^{L - 1}\left\lbrack {\left( {m_{k} - 1} \right){\prod_{l = {k + 1}}^{L}M_{l}}} \right\rbrack}} = i$${\prod\limits_{k = 1}^{L}M_{k}} = M$ wherein M_(k) represents a numberof the k^(th) layer of precoding branches, Δf_(k) represents a k^(th)layer of frequency offset and has a value determined in advance, k=1, 2,. . . L, T represents an offset period and has a value as follows:$T = \frac{1}{gc{d\left( {{\Delta f_{1}},{\Delta f_{2}},\ldots,{\Delta f_{L}}} \right)}}$wherein gcd(Δf₁, Δf₂, . . . , Δf_(L)) represents a greatest commondivisor of Δf₁, Δf₂, . . . , Δf_(L).